“十二五”发展时期中收入再分配是主要的政策目标,中国的社会统筹养老保险制度具有明显的收入再分配功能,本文着力研究社会统筹养老保险制度的收入再分配功能、福利分配的基尼系数和劳动者福利最大化之间的最优关系。本文依据劳动者的有效劳动能力将之分为三种类型:高劳动能力者,中劳动能力者和低劳动能力者,分别对应在国民财富第一次分配后所形成的高收入者、中收入者和低收入者。在这样的一个分析框架内,考虑社会统筹型的养老保险计划对不同收入水平的劳动者的生命周期效用的影响。本文发现:引入社会统筹型的养老保险计划会调节收入分配,提高低收入者的福利水平。当社会统筹制度的缴费率在合理范围内增加时将改进社会福利水平,同时福利分配的基尼系数将呈现下降的趋势,从而社会福利的分配将更趋于公平。而过高的缴费率会损害社会福利和分配公平。 The redistribution of income during the “Twelfth Five-Year Plan” period is the main policy goal. China’s social pooling pension insurance system has obvious redistribution of income. This paper focuses on the study of social redistribution of income and redistribution of welfare system The optimal relationship between the Gini coefficient and worker’s welfare maximization. This article is divided into three types according to the effective labor ability of laborers: those with high ability to work, those with medium ability to work and those with low ability to work, corresponding to the high income earners formed after the first distribution of national wealth, And low income earners. Within such an analytical framework, consider the impact of social pooling pension plans on the life-cycle utility of workers at different income levels. This paper finds that the introduction of a socially integrated pension insurance plan will adjust income distribution and raise the welfare of low-income earners. When the contribution rate of the social pooling system increases within a reasonable range, it will improve the level of social welfare. At the same time, the Gini coefficient of welfare distribution will show a downward trend, so the distribution of social welfare will be more fair. Excessively high contribution rates can undermine social welfare and distribute equity.